This application for a NIMH Independent Scientist Award(K02) requests support for the candidate's career goal of identifying strategies which can effectively intervene on the potential spiral of depression and functional disability in older adults. The K02 career development aims are: a) to foster collaborative study of these issues with an interdisciplinary set of scientists with clinical, biological, and psychosocial orientations, and b) to develop personal expertise in: i) theory and assessment of functional disability, and ii) methodology for assessing the feasibility and effectiveness of intervention strategies for reducing the causal effects of disability and depression on each other. The specific K02 research aims are to further the understanding of the relationship between depression and functional disability in elderly adults by testing hypotheses in data from both naturalistically treated and controlled treatment samples of elderly adults about: a) specific attributes of depression and disability that contribute to the risk of each condition over time, and b) the effect of systematic treatment interventions for depression on changes in functional disability in relationship to changes in depressive status. Depression and disability are both highly prevalent in advanced age and both associated with immense personal suffering, burden on family and expensive health care. Longitudinal population-based and clinical-based studies demonstrate that depression and disability affect each other's onset and course. The K02 award offers an opportunity to introduce the concept of heterogeneity to this research, both in terms of the severity and other clinical features of depression but also in terms of the assessment of functional disability. Disaggregating these phenomena and specifying attributes of depression and disability associated with the downward course of both promises two sets of scientific contributions. First, this research will identify specific mechanisms relating depression to functional disability in older adults. Second, it will identify potential avenues for effective intervention into these relationships in high risk populations.